How Much Improvement in Functional Status Is Considered Important by Patients With Active Psoriatic Arthritis: Applying

the Outcome Measures in Rheumatoid Arthritis Clinical Trials (OMERACT)

Group Guidelines

Philip Mease1 Rita Ganguly2, L. Wanke3, Amitabh Singh2

1Seattle Rheumatology Associates, Seattle, WA; 2Wyeth Research, Collegeville, PA; 3Amgen, Thousand Oaks, CA

Methods

• Data from a double blind, randomized, placebo controlled 24 weeks study was used to assess patients with active Psoriatic Arthritis treated with etanercept 25 mg twice weekly compared to placebo

• Alternative measures of MCID for improvement in patients’ functional status as measured by Health Assessment Questionnaire (HAQ) were:

– Data-driven MCID: 2.2.5– Patient Rating-Based MCID: 2.1.5– Patient Rating-Based Important MCID: 2.1.5

Methods

Data-Driven Approach MCIDData-Driven Approach MCID• Upper bound of 95% confidence interval of

standard error of measurement (SEM) for HAQ

• SEM = σ baseline HAQ 1- rbaseline HAQ

where σ=standard deviation

r = Cronbach’s alpha coefficient

Methods

Patient Rating-Based MCID

How important to you is the amount of change in your physical limitations (such

as limitations in walking, standing, gripping reaching, etc.) 1 2 3 4 5 6 7

Not At ExtremelyAll Important

Important

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Mean change from baselinein HAQ Disability Score for

those who improved

Minimally ImportantMinimally Important Very ImportantVery Important

Results

Threshold 95%for delta in Confidence Type of MCID

HAQ Scores Interval

SEM-Based MCID 0.40 N.A. 2.2.5Patient Rating-Based MCID 0.30 0.24-0.35 2.1.5Patient Rating-Based MajorClinically Important Difference

0.65 0.57-0.72 2.1.5

Valued Life Activities (VLA)

• Broader array of activities than measured by HAQ, e.g. ability to take part in social activities, taking care of family members, participating in religious activities, etc.

• Element of motivation

• Importance of meaningfulness

VLA

• Katz P Arth Care & Research 1995• RA patients with decline in basic function

and/or loss of valued activities• Deline in basic function (HAQ), no loss of

valued activities (30%)• Loss of valued activities, no decline in basic

function (57%)• Both (13%)